The present invention is concerned with an electronic component mounting system that mounts chip-components which are parts of electronic circuitry on a printed circuit board, in particular, relates to such a system which detects the positional error of a chip-component to be mounted by means of image processing, compensates the error, and mounts the chip-component on a printed circuit board at a correct position. Further the present invention is capable of handling any shape of components.
In the conventional chip-component mounting equipment, positioning of a chip-component being attracted by a vacuum fastener is performed by a mechanical positioning process called "centering" before it is mounted on a printed circuit board. For example, in the electronic component mounting equipment described in Japanese patent laid open publication No. 57-5395, the mounting head has two fastening nails at its tip, one is fixed to it and the other is supported rotatable by an axis that is fixed to that axis. A chip-component to be mounted is fastened by the two fastening nails and then positioning is performed mechanically. Another example is the automatic hybrid circuit board assembling equipment published in Japanese patent laid open publication No. 54-80558, whose positioning device has a pair of locators (each is called X axis line locator and Y axis line locator, respectively) that are supported freely rotatable by its spindle and a chip-component attracted at the tip of the spindle is fastened by the locators' tip parts and positioning is performed mechanically.
In the latter equipment, when a chip-component is positioned, it is mounted on a printed circuit board to which predetermined positions are applied some adhesive in advance for mounting. On the other hand, in the former equipment, a chip-component which is carried from its component supply part is handed over to said mounting head whose tip faces upward. In this condition, positioning is performed as explained. Then, with the chip-component, attracted at its tip, the mounting head begins to rotate downward to a printed circuit board and while rotating some adhesive is applied to the chip-component for mounting purpose. The mounting head stops when the chip-component at its tip faces the printed circuit board, and it is mounted on it as designed.
Also, in either equipment, the mounting head or the spindle, a kind of vacuum fastener, detects whether a chip-component is being attracted at its tip or not by means of vacuum level detection.
In the conventional equipment explained above, however, the following problems are pointed out as drawbacks.
As various kinds of different mechanical fasteners must be prepared for mounting various kinds of chip-component which are of different size and shape. This is not desirable for ease of handling.
In order to have the more precise positioning, the higher accuracy of machine tool technique for mechanical fasteners is required.
Holding or supporting a chip-component mechanically by this kind of fastener may cause the damage or breakage of the chip-component.
A component having protruded terminals like a discrete transistor is hard to be fastened by a fastener of this type.
In addition, in a prior electronic component mounting equipment, a chip-component is first handed over to be mounting head (a kind of fastener). This can cause a chip-component to be dropped before reaching the board.